Lathe assembly and method of using a lathe assembly

ABSTRACT

A lathe assembly having a guide with a passageway for movement of a piece of bar stock, with a leading end and a trailing end, in a substantially straight path between a feeding position and a working position. A sensor assembly is capable of detecting the position of the trailing end of a piece of bar stock within the guide passageway to thereby allow a user to determine if a piece of bar stock in the guide passageway has a length sufficient to perform the desired operation thereon. Also, a method of using the lathe assembly.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to lathe assemblies and, moreparticularly, to a lathe assembly which performs a machining operationon a piece of bar stock. The invention is also directed to a method ofusing a lathe assembly.

[0003] 2. Background Art

[0004] It is known to feed bar stock to a tool assembly and to machinethe bar stock in successive machining operations to produce multiple,finished workpieces from a single piece of the bar stock. In FIGS. 1-5herein, a conventional lathe assembly is shown at 10 for operating inthis manner upon individual pieces 12 of bar stock.

[0005] The lathe assembly 10 consists of a guide 14 defining apassageway 16 within which the individual pieces 12 of bar stock can beguidingly moved selectively towards and away from a spindle 18. Throughthe spindle 18, the pieces 12 of bar stock can be held in a workingposition, as shown in FIG. 2, and rotated. A tool assembly 20 performsmachining operations on the pieces 12 of bar stock in the workingposition to produce individual workpieces 22.

[0006] The pieces 12 of bar stock are delivered to the passageway 16from a supply location at 24 through a feed assembly 26. The feedassembly 26 consists of an endless chain conveyor 28 which is trainedaround spaced pulleys 30, 32. Through a drive 34, the pulley 32 isrotated selectively in a forward direction, as indicated by the arrows36 in FIG. 2, and a reverse direction, as indicated by the arrows 38 inFIG. 4.

[0007] A push rod 40 is attached to the upper surface of the chainconveyor 28 and is movable from left to right, with the drive 34operated to rotate the pulley 32 in the forward direction, and fromright to left, with the drive 34 operated to rotate the pulley 32 in thereverse direction. The push rod 40 has a receiver 42 at an end thereofto grip the trailing ends 44 of the pieces 12 of bar stock.

[0008] In operation, the pieces 12 of bar stock are delivered one-by-onefrom the supply location 24 to the top surface of the chain conveyor 28with the push rod 40 retracted to the FIG. 1 position. The drive 32 isthen activated to rotate the pulley 32 in the forward direction whichcauses the receiver 42 to advance from left to right and engage thetrailing end 44 of the active piece 12 of bar stock. Continued operationof the drive 34 causes the leading end 46 of the active piece 12 of barstock to be directed into and through the passageway 16 and spindle 18to be exposed outside of the spindle 18, as shown in FIG. 2, foroperation thereon by the tool assembly 20 to thereby produce a workpiece22.

[0009] The drive 34 is incrementally operated to advance the activepiece 12 of bar stock a distance equal to a predetermined lengthdimension for the workpiece 22. Eventually, the length of the activepiece 12 of bar stock is diminished to less than the predeterminedlength of the workpiece 22 that is to be produced. Attempting to machinethe remaining piece 12 of bar stock that is shorter than thepredetermined length of the workpiece 22 could cause jamming and, in anyevent, is a wasted step given that the machined workpiece 22 would haveto be sorted and discarded.

[0010] To avoid the above situation, it is known to use a proximitysensor 48 which detects an element 50 at the trailing end 44 of theactive piece 12 of bar stock. The element 50 is strategically situatedso that the proximity sensor 48 detects the element 50 once the activepiece 12 of bar stock has been reduced to a length less than thatnecessary to form the workpiece 22. After the last possible workpiece 22is formed, the sensor detects the element 50 and causes a signal to begenerated that causes the drive 32 to thereby retract the remainingpiece 12 of bar stock from the passageway 16 and release it to adisposal unit 54, as shown in FIG. 5.

[0011] The horizontal arrangement of the guide 14 is typical ofconventional lathe assemblies. One problem with this horizontalarrangement is that, with very long workpieces, a significant amount offloor space may be required to operate the lathe assembly.

[0012] While it is known to vertically orient elongate workpieces heldin a vertically opening chuck on lathe assemblies, the problem of chipbuildup on the workpiece and chuck must be contended with.

[0013] In FIGS. 12 and 13, two additional prior art lathe assemblies areshown at 58 and 60, respectively. The lathe assembly 58 is characterizedas a fixed spindle lathe assembly with there being a spindle 62 thereon,fixedly attached to a frame 63 and having a horizontal central axis 64.An elongate piece 12 of bar stock is advanced from an input end 68 ofthe spindle 62 through the spindle 62 to and through an output end 70 atwhich the piece 12 of bar stock is exposed to be machined by a toolassembly 72. The tool assembly 72 is selectively movable along X and Zaxes to allow a tool element 74 on the tool assembly 72 to operate onthe piece 12 of bar stock held and rotated by the spindle 62.

[0014] The lathe assembly 60 is characterized as a sliding spindle latheassembly and includes a spindle 76 with a horizontal central axis 78.The spindle 76 has an adaptor 80 which cooperates with, and is guidedalong, a rail 82 on a frame 84 so as to allow the spindle 76 to move inthe line of the double-headed arrow 86 parallel to the central axis 78of the spindle 76.

[0015] In the lathe assembly 60, a bushing assembly 88 is provided witha body 90 and a bushing 92 having an opening 94 therethrough. Thespindle axis 78 is coincident with the central axis for the bushingopening 94. The bushing assembly 88 serves as a support to rigidify theend of the piece 12 of bar stock that is being machined by a toolassembly 96.

[0016] Typically, both of the lathe assemblies 58, 60 are designed forrelatively small diameter pieces 12 of bar stock. It is conventional tomake dedicated machines that function either as a fixed spindle latheassembly, such as the lathe assembly 58, or as a sliding spindle latheassembly, such as the lathe assembly 60.

SUMMARY OF THE INVENTION

[0017] The invention is directed to a lathe assembly having a guide witha passageway for movement of a piece of bar stock, with a leading endand a trailing end, in a substantially straight path between a feedingposition and a working position. A sensor assembly is capable ofdetecting the position of the trailing end of a piece of bar stockwithin the guide passageway to thereby allow a user to determine if apiece of bar stock in the guide passageway has a length sufficient toperform a desired operation thereon.

[0018] The lathe assembly may further include a spindle for releasablyholding a piece of bar stock in the working position.

[0019] The sensor assembly may have a generator for a signal indicativethat a piece of bar stock in the guide passageway has less than apredetermined length.

[0020] The lathe assembly may further include a tool assembly to performan operation on a piece of bar stock in the working position.

[0021] The sensor assembly may include a generator for a stop signalindicative that a piece of bar stock in the guide passageway has lessthan the predetermined length. The lathe assembly may further include acontrol to receive the stop signal and, in response thereto, preventperformance of an operation by the tool assembly on a piece bar stock inthe passageway.

[0022] The sensor assembly may include an elongate element that can bedirected into the guide passageway to against the trailing end of apiece of bar stock in the passageway to thereby determine whether apiece of bar stock in the guide passageway is less than or greater thanthe predetermined length.

[0023] The sensor assembly may include a generator for a beam to bedirected against the trailing end of a piece of bar stock in the guidepassageway and reflected therefrom and a receiver for the reflectedbeam.

[0024] The generator may be a laser beam generator.

[0025] The lathe assembly may further include a piece of bar stock inthe guide passageway.

[0026] The lathe assembly may still further include a drive to rotate apiece of bar stock in the working position in the guide passageway.

[0027] The tool assembly may include a tool element which acts, againsta piece of bar stock in the working position. The tool assembly mayinclude a turret with a plurality of interchangeable tool elements.

[0028] In one form, the spindle has an axis and axially spaced input andoutput ends and the piece of bar stock in the working position projectsfrom both the input and output ends of the spindle.

[0029] In one form, the passageway has a central axis and axially spacedfirst and second ends. The spindle is at the first axially spaced endand the second axially spaced end is open to allow introduction of apiece of bar stock into the guide passageway.

[0030] The invention is also directed to a method of operating a latheassembly having a guide with a passageway with a central axis andaxially spaced first and second ends, a spindle, and a tool assembly forperforming an operation on a piece of bar stock having a length andleading and trailing ends. The method includes the steps of directing apiece of bar stock axially through the guide passageway in a firstdirection from a feeding position into a working position and directingan element into the guide passageway to detect the position of thetrailing end of the piece of bar stock and thereby determine if thepiece of bar stock in the guide passageway is less than or greater thanthe predetermined length.

[0031] The method may further include the step of performing anoperation on the piece of bar stock with the tool assembly if it isdetermined that the piece of bar stock has at least the predeterminedlength.

[0032] The method may further include the step of advancing the piece ofbar stock in the first direction after performing the operation andagain directing the element into the guide passageway to detect theposition of the trailing end of the piece of bar stock to againdetermine if the piece of bar stock in the guide passageway is less thanor greater than the predetermined length.

[0033] The step of directing an element from the sensor into the guidepassageway may involve the step of directing a laser beam into the guidepassageway.

[0034] The step of directing an element from the sensor into the guidepassageway may involve the step of directing an elongate element intothe guide passageway.

[0035] The method may further include the steps of providing a sensorassembly, generating a stop signal from the sensor assembly indicativethat the piece of bar stock has a length less than the predeterminedlength, and processing the stop signal so that no operation is performedby the tool assembly on the piece of bar stock in the guide passageway.

[0036] The invention is also directed to a lathe assembly with a guidehaving a passageway with a central axis for movement of a piece of barstock with a leading end and trailing end in a substantially straightpath substantially parallel to the central axis of the passagewaybetween a feeding position and a working position, and a spindle forreleasably holding a piece of bar stock in the working position andhaving a through opening with a central axis, an input end, arid anoutput end. The guide is oriented so that the central axis of thepassageway is not parallel to a horizontal support surface for the latheassembly. The passageway and through opening are aligned so that theleading end of a piece of bar stock can move through the passageway toand through the through opening from the input end to the output end toproject from the output end with a piece of bar stock in the workingposition.

[0037] The central axes of the passageway and through opening may besubstantially parallel to each other and extend substantiallyorthogonally to a horizontal support surface for the lathe assembly.

[0038] In one form, the central axes of the passageway and throughopening are substantially parallel to each other and are non-orthogonalto a horizontal support surface for the lathe assembly.

[0039] The lathe assembly may further include a tool assembly forperforming an operation on a piece of bar stock in the working position.

[0040] The invention is also directed to a method of operating a latheassembly with a guide having a passageway with a central axis andaxially spaced first and second ends, a spindle with a through openinghaving a central axis, an input end and an output end, and a toolassembly for performing an operation on a piece of bar stock having alength, a leading end, and a trailing end. The method includes the stepsof orienting the guide so that the central axis of the passageway isinclined relative to a horizontal support surface for the lathe assemblyand so that the central axis of the passageway declines from the firstend towards the second end of the passageway, directing the leading endof the piece of bar stock into and through the passageway in a firstdirection from the first end of the passageway towards the second end ofthe passageway, moving the leading end of the piece of bar stock in thefirst direction into and through the through opening to a workingposition wherein the leading end of the bar stock projects from theoutput end of the spindle, clamping the piece of bar stock in theworking position in the spindle, and performing an operation on aportion of the piece of bar stock projecting from the output end of thethrough opening with the piece of bar stock in the working position.

[0041] The method may further include the steps of placing a pluralityof pieces of bar stock, each having a length, in a storage position,with the lengths of the plurality of pieces of bar stock beingsubstantially parallel to each other and substantially parallel to ahorizontal surface supporting the lathe assembly, removing the pluralityof workpieces of bar stock one-by-one from the storage position, anddirecting the plurality of pieces of bar stock one-by-one into thepassageway.

[0042] The method may further include the steps of placing a pluralityof pieces of bar stock each having a length in a storage position withthe lengths of the plurality of pieces of bar stock being substantiallyparallel to each other and substantially non-parallel to a horizontalsurface supporting the lathe assembly, removing the plurality of piecesof bar stock one-by-one from the storage position, and directing theplurality of pieces of bar stock one-by-one into the passageway.

[0043] The invention is further directed to a lathe assembly having aspindle for holding an elongate workpiece and having a central axis, anda guide assembly having a body and a guide bushing on the body having afirst opening with a central axis. The spindle and guide assembly areselectively repositionable between a) a first relative position whereinthe central axis of the spindle extends through the first guide bushingopening so that an elongate workpiece held by the spindle can beprojected into the first guide bushing opening so that the guide bushinglimits flexing of an elongate workpiece held by the spindle and b) asecond relative position wherein the central axis of the spindle doesnot extend through the first guide bushing opening. The lathe assemblyfurther includes a tool assembly for performing an operation on anelongate workpiece held by the spindle.

[0044] In one form, with the spindle and guide assembly in the firstrelative position, the central axis of the spindle is substantiallycoincident with the central axis of the first guide bushing opening.

[0045] The guide bushing may be rotatable relative to the guide assemblybody around the central axis of the first guide bushing opening.

[0046] The lathe assembly may further be provided in combination with anelongate workpiece that is held by the spindle and projects into thefirst guide bushing opening with the spindle and guide assembly in thefirst relative position.

[0047] In one form, the guide assembly has a second opening in the bodywith a central axis and with the spindle and the guide assembly in thesecond relative position, the central axis of the spindle extendsthrough the second opening.

[0048] In one form, the first guide bushing opening has a firstdiameter, and the second opening has a second diameter, and the firstdiameter is different than the second diameter.

[0049] The guide assembly may be translatable relative to the spindle asthe spindle and guide assembly are repositioned between the firstrelative position and the second relative position.

[0050] The guide assembly may be rotatable about an axis relative to thespindle as the spindle and guide assembly are repositioned between thefirst relative position and the second relative position.

[0051] The spindle and guide assembly may be movable, one relative tothe other, along a line substantially parallel to the central axis ofthe spindle.

[0052] In one form, the spindle is abuttable to the guide assembly to besupported by the guide assembly.

[0053] In one form, with the spindle and the guide assembly in thesecond relative position, the central axis of the spindle issubstantially coincident with the central axis of the second opening.

BRIEF DESCRIPTION OF THE DRAWINGS

[0054]FIG. 1 is a schematic, cross-sectional view of a prior art latheassembly including a feed assembly for directing pieces of bar stockthrough a guide passageway to a spindle to be held thereby for operationby a tool assembly and with one of the pieces of bar stock placed on thefeed assembly;

[0055]FIG. 2 is a view as in FIG. 1 with the feed assembly operated toadvance the piece of bar stock through the guide passageway and spindleto a working position wherein it is exposed to be machined by the toolassembly;

[0056]FIG. 3 is a view as in FIG. 2 showing the piece of bar stockfurther advanced and with a workpiece formed and cut from the end of thepiece of bar stock;

[0057]FIG. 4 is a view as in FIG. 3 wherein the feed assembly isoperated to withdraw the remaining portion of the piece of bar stockfrom the spindle and guide passageway;

[0058]FIG. 5 is a view as in FIG. 4 with the remaining piece of barstock being deposited in a disposal unit;

[0059]FIG. 6 is a schematic, perspective view of a lathe assemblyaccording to the present invention;

[0060]FIG. 7 is a view as in FIG. 6 showing a spindle and tool assemblyon the lathe assembly;

[0061]FIG. 8 is an enlarged, schematic, cross-sectional view of a guidedefining a passageway, spindle, and a tool assembly for repositioningand advancing a piece of bar stock for operation thereon by a toolassembly on the inventive lathe assembly of FIGS. 6 and 7 and showingone type of structure, according to the present invention, fordetermining the remaining length of a piece of bar stock in the guidepassageway;

[0062]FIG. 9 is a view as in FIG. 8 showing another form of structurefor determining the remaining length of a piece of bar stock in theguide passageway;

[0063]FIG. 10 is a schematic representation of a lathe system, accordingto the invention, and having a non-horizontal guide passageway for asupply of pieces of bar stock, with the individual pieces beingdeliverable one-by-one from a supply in which the elongate bar stock issituated horizontally;

[0064]FIG. 11 is a view as in FIG. 10 with pieces of bar stock in asupply situated angularly to a horizontal support surface for the latheassembly for facilitated delivery to the guide passageway, and with amodification of the lathe assembly shown in phantom wherein the guideassembly extends substantially orthogonally to a horizontal supportsurface for the lathe assembly;

[0065]FIG. 12 is a schematic, side elevation view of a conventionallathe assembly having a fixed spindle;

[0066]FIG. 13 is a side elevation view of a conventional lathe assemblyhaving a slidable spindle;

[0067]FIG. 14 is a perspective view of a spindle in relationship to aguide assembly, according to the invention, and a tool assembly, withthe guide assembly and spindle being in a first relative positionwherein a piece of bar stock held by the spindle is supported on abushing on the guide assembly;

[0068]FIG. 15 is a view as in FIG. 14 with the spindle and guideassembly repositioned to a second relative position wherein the spindleabuts to the guide assembly and the piece of bar stock is not directlysupported by the guide assembly;

[0069]FIG. 16 is a fragmentary, plan view of the spindle and (guideassembly, according to the invention, arranged to function as a fixedspindle lathe assembly as in FIG. 14;

[0070]FIG. 17 is a fragmentary, plan view of the spindle and guideassembly, according to the invention, arranged to function as a slidingspindle lathe assembly as in FIG. 15; and

[0071]FIG. 18 is an elevation view of a modified form of guide assemblythat is useable in conjunction with the spindle in FIGS. 14-17.

DETAILED DESCRIPTION OF THE DRAWINGS

[0072] Referring initially to FIGS. 6-9, a lathe assembly, according tothe present invention, is shown at 100. The lathe assembly 100 includesan elongate guide 102 with a central axis 104. The guide 102 issupported by axially spaced frame elements 106,108, with the latterdefining a housing for a spindle 110 and a tool assembly 112, which areoperable to perform a machining operation on a piece 12 of bar stockheld by the spindle 110. The tool assembly 112 is a turret-type havinginterchangeable, and selectively usable, tool elements 113.

[0073] The guide 102 defines a passageway 114 through which pieces 12 ofbar stock can be delivered from a feeding position, as shown in FIG. 6,in a straight path to a working position, as shown in FIGS. 7-9. Thespindle 110 has a through opening 115 with an input end 116 and anoutput end 118. The through opening 115 and passageway 114 havecoincident central axes. As a piece 12 of bar stock is moved from thefeeding position into the working position, the leading end 46 thereofinitially enters the passageway 114 at an open axial end 119 thereof,extends along the axis 104 up to and beyond the input end 116 of thespindle 110, through the spindle 110 and from the output end 118 of thespindle 110 to be exposed adjacent to the tool assembly 112. Theadvancement of the piece 12 of bar stock can be effected by a pushingaction through the feed assembly 26, as previously described withrespect to claims 1-5, or by a feed assembly 26′ which grips and pullsthe pieces 12 of bar stock from the feeding position into the workingposition. The spindle 110 may be of any conventional construction.

[0074] Once in the working position, the active piece 12 of bar stock isheld by the spindle 110 whereupon the appropriate machining operation iscarried out by the tool assembly, as the spindle is rotated by a drive120 around the axis 104, to produce the finished workpiece 22. Theinitial length of the pieces 12 of bar stock can be selected to allowfabrication of numerous of the workpieces 22 from each length thereof.Accordingly, after each machining operation, the feed assembly 26, 26′can be operated to advance the active piece 12 of bar stock a setdistance as dictated by the length of the workpiece 22 to be formed.

[0075] According to the invention, the trailing end 44 of a piece 12 ofbar stock is monitored to thereby determine whether the remaining lengthof the piece 12 of bar stock in the guide passageway 114 is sufficientto perform a desired operation thereon by the tool assembly 112.

[0076] To accomplish this, a first type of sensor assembly is shown at121. The sensor assembly 121 includes a laser beam generator andreceiver 122 which is capable of directing a laser beam at the trailingend 44 of a piece 12 of bar stock and receiving the reflected beamsignal. With an appropriate control 124, an analysis of the impingingand reflecting beams can be made, after each advancing movement of thepiece 12 of bar stock, to ascertain the distance D between the laserbeam generator/receiver 122 and the trailing end 44 of the piece 12 ofbar stock. For a predetermined distance D, the remaining length of theactive piece 12 of bar stock will be insufficient to perform anoperation to produce a desired workpiece configuration. Upon identifyingthis predetermined distance, or greater, the control 124 sends a stopsignal 126 to a drive 128 for the tool assembly 112 and/or the drive 120to thereby prohibit operation of the tool assembly 112 on the remainingpiece 12 of bar stock. At the same time, or alternatively, the control124 may send a signal 130 to the feed assemblies 26, 26′ which may causethe feed assemblies 26, 26′ to stop and/or reverse the direction ofmovement of the remaining piece 12 of bar stock.

[0077] In FIG. 9, an alternative form of sensor assembly is shown at132. The sensor assembly 132 includes a drum 134 with a hub 136 aroundwhich a wire element 138 is wrapped. The wire element 138 has a free end140 which can be advanced into the passageway 114 by rotation of the hub136. The wire element 138 may be a single wire or a plurality of bundledwires. The wire may be spring wire, piano wire, ortho like. The degreeof rotation/number of rotations dictates the extension of the wireelement 138 within the passageway 114 to allow calculation of thedistance D1, which again is correlated to the length of the remainingpiece 12 of bar stock.

[0078] The rotation of the hub 136 can be detected by a control 142.Upon sensing the number of revolutions of the hub 136 which extends thewire element to a distance D1 indicative that the length of theremaining piece 12 of bar stock is less than that necessary to producethe desired configuration for the workpiece 22, the control 142generates a signal 144 to the drive 128 and/or one or both of the feedassemblies 26, 26′, as previously described.

[0079] In FIGS. 10 and 11, the guide 102 and frame element 108 are showninclined from the orientation in FIGS. 6-9 relative to a horizontalsupport surface 146 for the lathe assembly 100. Whereas the central axis104 is substantially parallel to the support surface 146 for the latheassembly 100 in FIGS. 6-9, in FIGS. 10 and 11, the axis 104 makes anangle α to the support surface 146. The angle α may range from a fewdegrees to 90°, as shown in dotted lines in FIG. 11.

[0080] The effective length L occupied by the guide 102 and frame 108 isreduced from the length L1 (FIG. 6) with the lathe assembly 100 in theFIG. 6 orientation. Since many facilities in which the lathe assembly100 would be operated have no significant height restriction, it ispossible to reduce the operating area of the floor required for thelathe assembly 100 by angularly situating the guide 102 and housing 108as in FIGS. 10 and 11.

[0081] In FIG. 10, the pieces 12 of bar stock are stacked so that thelengths thereof are substantially parallel to each other and the surface146. Through an appropriate transfer/feed mechanism 150, individualpieces 12 of bar stock can be reoriented and directed into thepassageway 114 through the open axial end 119 of the guide 102.

[0082] Alternatively, as shown in FIG. 11, a hopper 152 can be providedfor a supply of the pieces 12 of bar stock. The hopper 152 has a guidesurface 154 which is situated at an angle α equal to the angle α for theinclination of the guide 102 and frame element 108. Suitable structurecan be provided to discharge the pieces 12 of bar stock one-by-one fromthe hopper 152 by movement along the guide surface 154.

[0083] A further modification is shown in phantom lines in FIG. 10wherein the lathe assembly 100 is reversed so that the frame element 108is above the guide 102. The individual pieces 12 of bar stock would thushave to be fed against gravitational forces to a working position. Thisarrangement may be practical at relatively small angles α and forrelatively short pieces 12 of bar stock.

[0084] In FIGS. 14-17, a spindle 160 is shown in conjunction with aguide assembly 162 which allows the tool assembly at 164 to perform amachining operation on the piece 12 of bar stock held by the spindle 160both unsupported, with the fixed spindle arrangement as shown for thelathe assembly 58, and supported with the sliding spindle arrangement,as shown for the lathe assembly 60. Typically, this type of latheassembly is used to produce small diameter parts using bar stock on theorder of ⅛-¼ inch as opposed to 3-4 inches for the lathe assembly 100.

[0085] More specifically, the guide assembly has a body 166 with amounting opening 168 and a second opening 170 therethrough. The mountingopening 168 has a bushing 172 fit therewithin and in turn has an opening174 therethrough that is slightly greater in diameter than the diameterof the piece 12 of bar stock and of a lesser diameter than the secondopening. The second opening 170 is dimensioned to snugly receive areduced diameter portion 176 of the spindle 160. With the reduceddiameter portion 176 extended into the second opening 170, an annularsurface 178 abuts to a facing surface 180 on the body 1166.

[0086] According to the invention, the spindle 160 and body 166 aremounted to a frame 182 for guided movement between a first relativeposition, as shown in FIG. 14, and a second relative position as shownin FIG. 15. In the first relative position, the axis 184 of the spindle160 extends through the opening 174 and is coincident with the centralaxis 186 of the opening 174 and the central axis of the piece 12 of barstock held by the spindle 160. The bushing 172, which may be journalledfor rotation relative to the body 166, supports the leading end 46 ofthe piece 12 of bar stock near the location where it is operated upon bythe tool assembly 164.

[0087] By translatingly shifting one or both of the spindle 160 and body166 relative to the frame 182, and each other, in the direction of thedouble-headed arrow 188, the spindle 160 and guide assembly 162 can beplaced in the second relative position, wherein the central axis 184extends through the opening 170 and coincides with the central axis 190of the second opening 170. In the second relative position, the annularsurface 178 can be abutted to the surface 180. The diameter of thesecond opening 170 is significantly greater than the diameter of thepiece 12 of bar stock so that the spindle 160 can be rotated by a drive192 without there being any interference between the piece 12 of barstock and the body 166.

[0088] In the first relative position of FIG. 14, the spindle 160 andtool assembly 164 cooperate in the same manner as the spindle 76 andtool assembly 96 in FIG. 13. In the second relative position of FIG. 15,the spindle 160 and tool assembly 164 cooperate in the same manner asthe tool assembly 62 cooperates with the tool assembly 72 in FIG. 12.Thus, it is possible to use a single spindle 160 and a single latheassembly to operate in both modes disclosed in FIGS. 12 and 13.

[0089] A second drive 194 may also be used to move the spindle 160relative to the frame 182 along the axis 184. Additionally, oralternatively, the guide assembly 162 can be moved in the same linerelative to the frame 182 and spindle 160.

[0090] In FIG. 18, a modified form of guide assembly 195 is shown havinga body 196 which is rotatable around an axis 198 relative to the frame182 and spindle 160 between corresponding first and second relativepositions.

[0091] The body 196 has mounting and second openings 200, 202therethrough. By rotating the body 196 about the axis 198, the openings200, 202 can be repositioned so that the central axes thereofselectively can be brought into coincidence with the axis 184. Thesecond opening 202 has the same diameter as the opening 170, with themounting opening 200 having a corresponding diameter to the firstopening 168. A like bushing 204 can be mounted in the opening 200 and inturn has an opening 206, corresponding to the opening 174, to accept thepiece 12 of stock material.

[0092] The foregoing disclosure of specific embodiments is intended tobe illustrative of the broad concepts comprehended by the invention.

1. A lathe assembly comprising: a guide having a passageway for movementof a piece of bar stock, with a leading end and a trailing end, in asubstantially straight path between a feeding position and a workingposition; and a sensor assembly capable of detecting the position of thetrailing end of a piece of bar stock within the guide passageway tothereby allow a user to determine if a piece of bar stock in the guidepassageway has a length sufficient to perform a desired operationthereon.
 2. The lathe assembly according to claim 1 further comprising aspindle for releasably holding a piece of bar stock in the workingposition.
 3. The lathe assembly according to claim 1 wherein the sensorassembly comprises a generator for a signal indicative that a piece ofbar stock in the guide passageway has less than a predetermined length.4. The lathe assembly according to claim 1 further comprising a toolassembly to perform an operation on a piece of bar stock in the workingposition.
 5. The lathe assembly according to claim 4 wherein the sensorassembly comprises a generator for a stop signal indicative that a pieceof bar stock in the guide passageway has less than a predeterminedlength and the lathe assembly further comprises a control to receive thestop signal and in response thereto prevent performance of an operationby the tool assembly on a piece of bar stock in the passageway.
 6. Thelathe assembly according to claim 1 wherein the sensor assemblycomprises an elongate element that can be directed into the guidepassageway to against the trailing end of a piece of bar stock in thepassageway to thereby determine whether a piece of bar stock in theguide passageway is less than or greater than a predetermined length. 7.The lathe assembly according to claim 1 wherein the sensor assemblycomprises a generator for a beam to be directed against the trailing endof a piece of bar stock in the guide passageway and reflected therefromand a receiver for the reflected beam.
 8. The lathe assembly accordingto claim 1 in combination with a piece of bar stock in the guidepassageway.
 9. The lathe assembly according to claim 1 furthercomprising a drive to rotate a piece of bar stock in the workingposition in the guide passageway.
 10. The lathe assembly according toclaim 4 wherein the tool assembly comprises a tool element which actsagainst a piece of bar stock in the working position and the toolassembly further comprises a turret with a plurality of interchangeabletool elements.
 11. The lathe assembly according to claim 8 wherein thespindle has an axis and first axially spaced input and output ends andthe piece of bar stock in the working position projects from both theinput and output ends of the spindle.
 12. The lathe assembly accordingto claim 7 wherein the generator is a laser beam generator.
 13. Thelathe assembly according to claim 2 wherein the passageway has a centeraxis and axially spaced first and second ends, the spindle is at thefirst axially spaced end and the second axially spaced end is open toallow introduction of a piece of bar stock into the guide passageway.14. A method of operating a lathe assembly comprising a guide having apassageway with a central axis and axially spaced first and second ends,a spindle, and a tool assembly for performing an operation on a piece ofbar stock having a length and leading and trailing ends, said methodcomprising the steps of: directing the piece of bar stock axiallythrough the guide passageway in a first direction from a feedingposition into a working position; and directing an element into theguide passageway to detect the position of the trailing end of the pieceof bar stock and thereby determine if the piece of bar stock in theguide passageway is less than or greater than a predetermined length.15. The method of operating a lathe assembly according to claim 14further comprising the step of performing an operation on the piece ofbar stock with the tool assembly if it is determined that the piece ofbar stock has at least the predetermined length.
 16. The method ofoperating a lathe assembly according to claim 15 including the step ofadvancing the piece of bar stock in the first direction after performingthe operation and again directing the element into the guide passagewayto detect the position of the trailing end of the piece of bar stock toagain determine if the piece of bar stock in the guide passageway isless than or greater than the predetermined length.
 17. The method ofoperating a lathe assembly according to claim 14 wherein the step ofdirecting an element into the guide passageway comprises the step ofdirecting a laser beam into the guide passageway.
 18. The method ofoperating a lathe assembly according to claim 14 wherein the step ofdirecting an element into the guide passageway comprises the step ofdirecting an elongate element into the guide passageway.
 19. The methodof operating a lathe assembly according to claim 14 further comprisingthe steps of providing a sensor assembly, generating a stop signal fromthe sensor assembly indicative that the piece of bar stock has a lengthless than the predetermined length, and processing the stop signal sothat no operation is performed by the tool assembly on the piece of barstock in the guide passageway.
 20. A lathe assembly comprising: a guidehaving a passageway with a central axis for movement of a piece of barstock with a leading end and a trailing end in a substantially straightpath substantially parallel to the central axis of the passagewaybetween a feeding position and a working position; and a spindle forreleasably holding a piece of bar stock in the working position andhaving a through opening with a central axis, an input end and an outputend, the guide oriented so that the central axis of the passageway isnot parallel to a horizontal support surface for the lathe assembly, thepassageway and through opening being aligned so that the leading end ofa piece of bar stock can move through the passageway to and through thethrough opening from the input end to the output end to project from theoutput end with a piece of bar stock in the working position.
 21. Thelathe assembly according to claim 20 wherein the central axes of thepassageway and through opening are substantially parallel to each otherand extend substantially orthogonally to a horizontal support surfacefor the lathe assembly.
 22. The lathe assembly according to claim 20wherein the central axes of the passageway and through opening aresubstantially parallel to each other and are non-orthogonal to ahorizontal support surface for the lathe assembly.
 23. The latheassembly according to claim 20 further comprising a tool assembly forperforming an operation on a piece of bar stock; in the workingposition.
 24. The lathe assembly according to claim 20 wherein thepassageway declines toward the spindle so that a piece of bar stock isurged under its own weight toward the working position.
 25. A method ofoperating a lathe assembly comprising a guide having a passageway with acentral axis and axially spaced first and second ends, a spindle with athrough opening having a central axis, an input end and an output end,and a tool assembly for performing an operation on a piece of bar stockhaving a length, a leading end, and a trailing end, said methodcomprising the steps of: orienting the guide so that the central axis ofthe passageway is inclined relative to a horizontal support surface forthe lathe assembly so that the central axis of the passageway declinesfrom the first end toward the second end of the passageway; directingthe leading end of the piece of bar stock into and through thepassageway in a first direction from the first end of the passagewaytoward the second end of the passageway; moving the leading end of thepiece of bar stock in the first direction into and through the throughopening to a working position wherein the leading end of the bar stockprojects from the output end of the spindle; clamping the piece of barstock in the working position in the spindle; and performing anoperation on a portion of a piece of bar stock projecting from theoutput end of the through opening with a piece of bar stock in theworking position.
 26. The method of operating a lathe assembly accordingto claim 25 further comprising the steps of placing a plurality ofpieces of bar stock, each having a length, in a storage position withthe lengths of the plurality of pieces of bar stock being substantiallyparallel to each other and substantially parallel to a horizontalsurface supporting the lathe assembly, removing the plurality of piecesof bar stock one-by-one from the storage position, and directing theplurality of pieces of bar stock one-by-one into the passageway.
 27. Themethod of operating a lathe assembly according to claim 25 furthercomprising the steps of placing a plurality of pieces of bar stock, eachhaving a length, in a storage position with the lengths of the pluralityof pieces of bar stock being substantially parallel to each other andsubstantially non-parallel to a horizontal surface supporting the latheassembly, removing the plurality of pieces of bar stock one-by-one fromthe storage position, and directing the plurality of pieces of bar stockone-by-one into the passageway.
 28. A lathe assembly comprising: aspindle for holding an elongate workpiece and having Et central axis; aguide assembly having a body and a guide bushing on the body having afirst opening with a central axis, the spindle and guide assembly beingselectively repositlionable between a) a first relative position whereinthe central axis of the spindle extends through the first guide bushingopening so that an elongate workpiece held by the spindle can beprojected into the first guide bushing opening so that the guide bushinglimits flexing of an elongate workpiece held by the spindle and b) asecond relative position wherein the central axis of the spindle doesnot extend through the first guide bushing opening; and a tool assemblyfor performing an operation on an elongate workpiece held by thespindle.
 29. The lathe assembly according to claim 28 wherein with thespindle and guide assembly in the first relative position the centralaxis of the spindle is substantially coincident with the central axis ofthe first guide bushing opening.
 30. The lathe assembly according toclaim 28 wherein the guide bushing is rotatable relative to the guideassembly body around the central axis of the first guide bushingopening.
 31. The lathe assembly according to claim 28 in combinationwith an elongate workpiece that is held by the spindle and projects intothe first guide bushing opening with the spindle and guide assembly inthe first relative position.
 32. The lathe assembly according to claim28 wherein the guide assembly comprises a second opening in the bodywith a central axis, and with the spindle and the guide assembly in thesecond relative position the central axis of the spindle extends throughthe second opening.
 33. The lathe assembly according to claim 32 whereinthe first guide bushing opening has a first diameter, the second openinghas a second diameter, and the first diameter is different than thesecond diameter.
 34. The lathe assembly according to claim 28 whereinthe guide assembly is translatable relative to the spindle as thespindle and guide assembly are repositioned between the first relativeposition and the second relative position.
 35. The lathe assemblyaccording to claim 28 wherein the guide assembly is rotatable about anaxis relative to the spindle as the spindle and guide assembly arerepositioned between the first relative position and the second relativeposition.
 36. The lathe assembly according to claim 28 wherein thespindle and guide assembly are movable, one relative to the other, alonga line substantially parallel to the central axis of the spindle. 37.The lathe assembly according to claim 28 wherein the spindle isabuttable to the guide assembly to be supported by the guide assembly.38. The lathe assembly according to claim 32 wherein with the spindleand the guide assembly in the second relative position the central axisof the spindle is substantially coincident with the central axis of thesecond opening.